Research has suggested that up to 75% of US adults are vitamin D deficient, leaving many running to pharmacy shelves to add vitamin D capsules to their supplement plan, and for good reason. The fat soluble vitamin obtained through sun exposure, fish and fortified foods promotes calcium absorption in the gut, preventing osteoporosis. Vitamin D may also play a role in the prevention of colon, prostate and breast cancers. Animal studies have shown an even greater impact of vitamin D suggesting that it may have an influence in the prevention and treatment of type I and type II diabetes and multiple sclerosis.
With all of the positive press, many are starting to take mega doses of vitamin D, leaving the potential of toxicity. The side effects of vitamin D toxicity include anorexia, heart arrythimias, polyuria and more seriously increased the risk of cardiovascular mortality. Considering cardiovascular disease is the leading cause of death in the western world and vitamin D is quickly becoming America’s most popular supplement the association with cardiovascular disease is an important topic.
In the largest study of its kind, scientists from the University of Copenhagen sought to compare vitamin D levels in 250,000 patients with morbidity and mortality related to cardiovascular disease. Serum vitamin D levels were analyzed and found an interesting correlation. Not only were patients with low levels of vitamin D at a higher risk for cardiovascular related death, but patients with very high levels were at a higher risk as well. With higher mortality rates attributed to heart attack and stroke observed in both groups. The study suggests that vitamin D levels below 50 or over 100 nmol/liter are associated with cardiovascular death. With 70 nmol/liter showing to have the lowest risk of death. Of course, correlation does not mean causation, but the study does highlight the problem with over supplementation. We are still unsure about the long term side effects of many of the supplements we are taking.
Unless other wise prescribed by a doctor the best sources of vitamin D remain from limited sun exposure, the flesh of fatty fish such as salmon, tuna and mackerel, and foods fortified with vitamin D.
Sources
Darshana Durup, Henrik Løvendahl Jørgensen, Jane Christensen, Anne Tjønneland, Anja Olsen, Jytte Halkjær, Bent Lind, Anne-Marie Heegaard, Peter Schwarz. A reverse J-shaped association between serum 25-hydroxyvitamin D and cardiovascular disease mortality – the CopD-study. The Journal of Clinical Endocrinology & Metabolism, 2015; jc.2014-4551 DOI: 10.1210/jc.2014-4551
NIH-http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
About the Author
Jarrott received a Masters degree in exercise physiology from San Diego State University in 2012 where he became a certified ACSM Health Fitness Specialist. Prior to BaySport, Jarrott spent time working as an exercise physiologist with UC San Francisco Human Performance Center and the Department of Warfighter Performance with the Naval Health Research Center. Weekends and night are spent getting outdoors to hike and play basketball.
